Along with the recent miniaturization and increased speed of a CPU, and the enhancement of a screen display speed and precision in a small and light-weight display apparatus such as a liquid crystal display apparatus, portable terminals such as a mobile telephone and a personal digital assistant (PDA) are also being miniaturized and reduced in weight. In such a small portable terminal and the like, it is physically difficult to provide an input interface such as a keyboard, and there is a limit to the reduction in input time in a thumb-input interface as in a mobile telephone, so that an input interface for inputting a handwritten character and a handwritten graphic is often provided.
However, generally in a small portable terminal and the like, a display screen is usually very small due to the physical constraint thereof. In the case of inputting a handwritten character or graphic on such a small display screen, a display area in which the character or graphic is to be input is not necessarily large enough, and there is also a limit to the increase in resolution of a display screen due to the physical constraint of the display area.
In order to solve the above-mentioned problem, various handwriting-input methods have been proposed. For example, JP2939119 discloses a handwriting-input method in which an input mode and a display mode are switched based on the behavior of a pen in an input display area. According to this method, a relatively large input display area is kept by scrolling or the like, and thereafter, a handwritten character or the like is input in the input mode. Then, the input mode is switched to the display mode, and stroke data on the input handwritten character or the like is normalized so as to be matched with the position and size specified in the display area, whereby the handwritten character or the like can be input at a desired position. The method for normalizing an input handwritten character is disclosed in detail by JP3268029, JP10(1998)-91346A, and the like. By switching a mode as described above, a sufficient area for input can be kept at a time of an input, and a display with an appropriate size can be performed at a time of a display. Thus, the physical constraint of the display screen can be eliminated.
Furthermore, JP8(1996)-185266A discloses a method for adjusting the variation of characters at a time of a display, while allowing stroke data and a bit image to be mixed. JP6(1994)-124164A discloses a method for inputting a pencraft on a screen enlarged by a predetermined magnification at a time of a handwriting-input, and displaying the input pencraft with a reduced size corresponding to a display screen at a time of viewing. In any method, a pencraft is input in a relatively large area at a time of an input, and a displayed pencraft is normalized in accordance with the constraint of a display area, whereby the physical constraint of a display screen is eliminated.
According to the above-mentioned method, an input pencraft is reduced in size, so that even when a display area is small, a relatively large number of pencrafts can be written. However, it is required to previously specify writing positions of the pencrafts. Furthermore, even a pencraft input as a graphic is considered as a character, and normalized to a predetermined size, so that a graphic cannot be input. Thus, in the case where it is necessary to input a mixture of a character and a graphic, a user needs to input a pencraft consciously by specifying an input mode regarding whether a character or a graphic is to be input next. Thus, there is a problem that a so-called free handwriting memorandum cannot be realized.
Furthermore, there is a time lag from a time when a pencraft is input in an input area to a time when the input pencraft is displayed in a display area. Therefore, in some cases, the user has to be in a stand-by state until the pencraft is input at a predetermined position.
Furthermore, although a pencraft can be written on an enlarged input screen at a time of an input, since a display area is enlarged, the area where a pencraft can be actually input is relatively narrow. Therefore, in order to input a number of characters, an unwritten input area needs to be displayed by scrolling or the like frequently, which makes an operation itself cumbersome.